The present invention relates to a method of cleaning a pressurized container having chemicals stored or otherwise contained therein. Specifically, the present invention relates to a method of cleaning pressurized containers such as, for example, rail tank cars, mobile tanks or the like. Further, the chemicals may be any material stored under pressure that may be difficult to collect and dispose of due to the hazardous characteristics thereof.
It is, of course, generally known to store and/or transport chemicals having hazardous characteristics via pressurized containers. Further, it is also generally known to clean these containers using a variety of methods and systems. In the past, cleaning pressurized containers entailed venting excess gaseous material to the atmosphere. Further, unpressurized containers contained bottom hatches or valves for draining liquid chemicals. However, many hazardous chemicals escaped into the environment thereby causing health risks for humans, vegetation and wildlife. With the advent of environmental standards and compliance, however, venting or draining hazardous chemicals to the environment has generally become illegal. Today, the chemicals are typically routed to a flare to be incinerated or otherwise collected for disposal.
However, while some of the gases contained within the containers may be relatively easy to recover and dispose of by venting of the pressurized containers to a flare, it is difficult to remove all of the gases contained therein. Further, liquid product may remain inside a container after cleaning. Typical systems and methods of cleaning may involve injecting the container with a quantity of steam that may aid in bringing the liquid chemicals to the gaseous phase. The steam/gaseous chemical product combination is transported from the container for incineration or disposal. However, problems may occur using steam to remove chemicals from pressurized containers since steam may condense within the container forming liquid water or ice. The liquid water or ice may mask the presence of the chemicals from detectors. Further, the liquid water or ice may interfere with the removal of the chemicals from the container.
Another method of removal, especially for unpressurized containers having liquid therein, may include entering the container to manually remove the chemical. While this may be a relatively efficient and thorough way to remove the chemical from the container, it may be very dangerous, as it requires an individual to actually enter the container thereby exposing the individual to the chemicals contained therein. Further, by opening the container, there may be a significant risk that some of the chemicals may escape into the environment.
Therefore, an improved method of cleaning pressurized containers is necessary. Particularly, a method is needed that overcomes the problems associated with typical cleaning methods. Further, a method is needed that cleanly and efficiently moves chemical product from a pressurized container and transports the waste product to a proper disposal system such as a flare for incineration.
The present invention relates to a method of cleaning a pressurized container having chemicals therein. More specifically, the present invention allows containers such as, for example, rail tank cars, to be cleaned safely and efficiently without risking exposure of the chemicals to people or the environment. The invention entails injecting heated and pressurized nitrogen gas into the container thereby purging the container of any chemical therein to form a nitrogen/chemical mixture. The nitrogen/chemical mixture may then be sent to a flare for incineration. Further, the heated nitrogen gas may aid in pulling the chemical out of the container and transporting the chemical to the flare for incineration.
To this end, in an embodiment of the present invention, a method of cleaning a container having at least one chemical therein is provided, the method comprises providing a container having an amount of at least one chemical contained therein wherein the container has a plurality of valves for adding material to the container or removing material from the container and adding an amount of heated nitrogen gas to the container to mix with the chemical creating a nitrogen gas/chemical mixture. Further, the method comprises providing a flare to incinerate the chemical and venting the nitrogen gas/chemical mixture to the flare.
In an embodiment of the present invention, the chemical is in a gaseous state at standard temperature and pressure and further wherein the chemical has a pressure within the container.
In an embodiment of the present invention, the method further comprises the steps of measuring the pressure within the container prior to adding the heated nitrogen gas and venting the gaseous chemical to the flare.
In an embodiment of the present invention, the method further comprises the step of inspecting the container for leaks.
In an embodiment of the present invention, the method further comprises the step of sampling the hazardous material to verify the identity of the chemical.
In an embodiment of the present invention, the method further comprises the step of attaching a pipe to one of the valves and connecting the pipe to the flare prior to venting the residual pressure of the chemical.
In an embodiment of the present invention, the method further comprises the steps of providing a housing having sideports wherein the housing is disposed over the valves and sampling the gas within the housing for leaks via the sideports of the housing while inspecting the container.
In an embodiment of the present invention, the method further comprises the steps of providing a lid on the housing, opening the lid and inspecting the valves in the housing for damage to the valves.
In an embodiment of the present invention, the temperature of the heated nitrogen gas is between about 100xc2x0 F. and about 300xc2x0 F.
In an embodiment of the present invention, the method further comprises the step of attaching a pipe from the nitrogen gas to the inlet valve of the container.
In an embodiment of the present invention, the method further comprises the steps of filling the container with heated nitrogen gas, venting the heated nitrogen gas from the container and repeating filling and venting a plurality of times until the concentration of the chemical therein reaches a predefined amount.
In an embodiment of the present invention, the method further comprises the step of adding heated nitrogen gas until the pressure within the container is between about 5 psi and about 50 psi.
In an embodiment of the present invention, the method further comprises the step of grounding the container prior to inspecting the container.
In an embodiment of the present invention, the method further comprises the steps of providing a means to access the inside of the container and opening the means to access the inside of the container to gain access to the inside of the container.
In an embodiment of the present invention, the method further comprises the steps of providing steam in a steam tank, connecting a pipe from the steam tank to the inlet valve of the container, adding the steam to the container to pressurize the container with the steam, and maintaining the pressure of the steam within the container for an amount of time.
In an embodiment of the present invention, the method further comprises the steps of measuring a residual pressure of the chemical within the container with a pressure gauge prior to adding the amount of heated nitrogen gas, and venting the residual pressure of the hazardous material to the flare.
In an embodiment of the present invention, the method further comprises the step of adding a quantity of heated nitrogen gas if the residual pressure within the container is about zero psi.
In an embodiment of the present invention, the container is a rail tank car.
In an embodiment of the present invention, the container has a plurality of chemicals contained therein.
In an embodiment of the present invention, the method further comprises the steps of providing a control panel having a plurality of controls for controlling the cleaning method and controlling the cleaning method via the control panel.
It is, therefore, an advantage of the present invention to provide a method of cleaning a pressurized container having a quantity of chemicals therein that safely and efficiently removes chemicals from the container. Moreover, it is advantageous that the present invention removes chemicals from the container without risking exposure to people or the environment.
Further, it is an advantage of the present invention to provide a method of cleaning a pressurized container having a quantity of chemicals therein that allows the chemicals to be removed without causing damage to the container by freezing the container or pipes connected thereto. In addition, an advantage of the present invention is that the heated nitrogen gas used to remove the product will not condense within the container and therefore will not mask the presence of the chemicals therein.
Another advantage of the present invention is to provide a method of cleaning a pressurized container having a quantity of chemicals therein that is largely automatic and therefore allows an individual to monitor the process without exposing the individual to the chemicals. Additionally, an advantage of the present invention is that a plurality of types of containers may be cleaned using the method and method defined herein, including, but not limited to, rail tank cars and other like containers.
Additional features and advantages of the present invention are described in and will be apparent from, the detailed description of the presently preferred embodiments and from the drawings.